Laboratory test comparative study on open-close piles during jacked pile-jacking based on pile-soil interface stress measurement

In order to explore the mechanical mechanism of pile-jacking in clay soil, a large-scale laboratory model test of pile-jacking in open and closed pile in saturated clay soil was carried out, and the change law of excess pore pressure and earth pressure at pile-soil interface caused by pile-jacking in open and closed pile was obtained. At the same time, the effective earth pressure at the pile-soil interface was calculated according to the principle of effective stress, and the ratio of effective earth pressure to horizontal dead weight stress was regarded as the adhesion coefficient between pile and soil, and the determination method of the degree of adhesion between pile and soil during pile jacking was established. The results show that the excess pore water pressure and earth pressure at the pile-soil interface of closed pile are larger than that at the open pile. With the increase of pile depth, the excess pore water pressure and earth pressure of open-close piles at the pile-soil interface increase gradually, and the closer the pile is to the pile end, the greater the excess pore water pressure and earth pressure at the pile-soil interface are. The phenomenon of "lateral pressure degradation" exists in the earth pressure and effective earth pressure of open and closed pile interface at the same depth. The greater the depth of burial, the greater the coefficient of adhesion between piles and soil, and the higher the degree of adhesion between piles and soil. The determination of the degree of adhesion between piles and soils is related to the excess pore water pressure and earth pressure caused by jacking piles, which reflects the mechanical mechanism of jacking piles in saturated clay. © 2021, Central South University Press. All right reserved.